9/80 Compressed Work Schedule Calculator
The 9/80 fortnight
The 9/80 is one of those patterns that sounds fiddly when you read the name and turns out to be simple once you see it laid out. The whole thing is built around the fortnight rather than the week. You work the same 80 hours you'd work on a normal Monday-to-Friday job over two weeks — you just pack them into 9 days instead of 10, and the day you save becomes a day off.
Here's how the hours fall. You work eight 9-hour days and one 8-hour day across the fortnight. In practice that usually means Monday to Thursday at 9 hours in both weeks, a full 8-hour Friday in one of those weeks, and the Friday in the other week off entirely. Eight nines and an eight comes to 80, spread over 9 working days. That's the definition of the pattern, and everything else is just where the longer hours land on the clock.
Those 9-hour days are the part you actually feel. If you're used to clocking off at five, a 9/80 day typically stretches that to six, or starts you earlier in the morning — it depends entirely on how your employer sets the start and finish times. It's only an hour, but an hour at the end of an already-long day has a way of mattering more than it looks on paper, especially once you factor in the commute home. Most people I've spoken to settle into it within a couple of weeks and stop noticing, but it's worth going in with your eyes open rather than assuming the day off comes for free.
One detail that trips people up early on is the changeover. Because the pattern runs on a two-week loop, there's a long Friday in one week and no Friday at all in the next. If you're new to it, your sense of "which week is this?" takes a little while to settle. That's genuinely the hardest part of the 9/80, and it's exactly the bit a calendar is good at — once you can see the whole fortnight mapped out, the rhythm stops being something you have to remember and just becomes something you glance at.
That extra day off
The reason anyone puts up with the longer days is the prize at the end of it: a day off every other week, on top of your normal weekend. For most people on the 9/80 that's every other Friday, which turns one weekend in two into a three-day weekend. Some employers run it the other way and give you alternate Mondays instead, which is the same deal pointing in the opposite direction — a long weekend that starts on Saturday and rolls into Monday.
It doesn't sound like much until you have one. A free weekday is a different thing from a free Saturday. Banks, doctors, dentists, garages, the council, anyone you can only ever reach during office hours — suddenly you can deal with them without burning a holiday day or trying to sneak out at lunch. School pickups, a long appointment, a quiet morning before everyone else surfaces: the off-Friday absorbs all the admin that normally eats into your actual weekend, and the Saturday and Sunday stay yours.
The flip side is honest enough to name. On your off-Friday colleagues on a normal schedule are still working, so emails and messages keep arriving, and if you're not careful the "day off" quietly becomes a half-day of catching up. The people who get the most out of the 9/80 tend to be firm about it — out of office on, notifications down, and the day treated as properly off. The pattern gives you the time; protecting it is on you.
It's also worth knowing where you stand if the day you'd normally have off lands on a bank holiday, because employers handle that differently. Some shift your free day, some let the two cancel out. That's a conversation to have with your manager rather than something to assume — and once you know the rule, you can mark it on the calendar so there are no surprises later in the year.
Where the 9/80 fits
The 9/80 is an office and engineering schedule, not a round-the-clock one. You'll find it in aerospace and defence, with government contractors, in professional services and on plenty of technical and engineering teams. What those workplaces have in common is that the work gets done in a predictable weekday window — there's no till to keep open and no ward to keep staffed, so the question of when exactly you're at your desk has more give in it.
That's why this pattern sits a bit apart from most of the others on this site. The rotating patterns — your 4-on-4-off, your 2-2-3, the continental — exist to cover something continuously, around the clock, seven days a week. The 9/80 isn't about coverage at all. Nobody needs a desk manned at 2am, so the schedule can be shaped around the people doing the work rather than the hours that need filling. It's a perk dressed up as a schedule, really, which is exactly why companies offer it.
If your job does involve shift coverage — healthcare, manufacturing lines, emergency services, anything that has to keep running when you're not there — the 9/80 probably isn't what you're on, and one of the rotating patterns linked at the bottom of this page will fit better. The 9/80 only works when the work can wait for you to come back. For the jobs where it does fit, it's one of the most popular flexible arrangements going, and once you've had the alternate Fridays it's a hard thing to give up.
Working out your 9/80 calendar
The calculator at the top of the page does the counting so you don't have to. The 9/80 is already selected, so there's only one thing it needs from you: which week is your reference week — the week where you work the full Friday rather than taking it off. Set that, and the pattern locks into place for the whole year.
- Set your reference week. Pick the week where you work the long, full Friday. If you're not sure, find the most recent Friday you had off and count forward — the next Friday you work is your reference. Not certain? Your HR team or rota will confirm it.
- Generate the year. The calendar fills in all twelve months at once: every 9-hour day, every off-Friday (or off-Monday) and the bank holidays for your country, so the whole fortnightly rhythm is there to glance at.
- Check a date or export it. Use the date checker in the sidebar to test a specific day — handy when you're booking something months ahead — or export the calendar straight to your phone so your off-days travel with you.
9/80 questions answered
What does the 9/80 schedule actually mean?
It means you work a full fortnight of 80 hours over 9 days instead of the usual 10. You do eight 9-hour days and one 8-hour day, and the day you'd otherwise have worked becomes a day off — typically every other Friday. The name is just the structure spelled out: 9 working days, 80 hours.
How are the hours arranged across the fortnight?
Across the two weeks you work Monday to Thursday at 9 hours a day in both weeks. One of those weeks you also work a full 8-hour Friday; the other week that Friday is off. Eight nines plus one eight gives you 80 hours over 9 working days. The longer weekday is the trade you make for the day off.
Which day do you get off, and how does it alternate?
Most employers give you every other Friday off, though some run it as alternate Mondays. Either way it cycles on a two-week loop, so the same weekday comes free once a fortnight. Whether this Friday or the next one is yours depends on which week is your reference week — set that above and the calendar marks every off-day for the year.
Who tends to use the 9/80?
It's mostly an office and engineering arrangement — aerospace and defence, government contractors, professional services and tech teams. It suits work done in a predictable weekday window rather than continuous round-the-clock coverage, which is why you rarely see it in healthcare, manufacturing lines or emergency services.
How do I map out which Fridays I'll have off?
Tell the calculator which week is your reference week — the one where you work the full Friday — and it lays out the entire year. Every off-Friday, every long day and the bank holidays appear on one calendar, you can test a specific date with the date checker, and you can export the whole thing to your phone.
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